# If $I_n =\int x^n. e^{ex} dx$ for $n \geq 1$ then $C.I_n+n.I_{n-1}=$

$\begin {array} {1 1} (1)\;x^ne^{ex} & \quad (2)\;x^n \\ (3)\;e^{ex} & \quad (4)\;x^n+e^{ex} \end {array}$